DE69632743T2 - METHOD FOR REGULATING VAGALTONUS - Google Patents

Abstract

The present invention provides methods of altering vagal tone in a patient by administering a therapeutically effective amount of a mediator of P2x-purinoceptors located on vagal afferent nerve terminals to the patient. Diagnostic applications are also provided.

Description

Territory of invention

The The present invention relates to the regulation of vagus tone in human patient.

background the invention

Of the parasympathetic branch, d. H. the vagus, is a major component of the autonomic nervous system, which has the function of many different Organs and tissues throughout the body controls. Release sensory stimuli neural signals (i.e., action potentials) which in the vagus are afferent Fibers migrate to the central nervous system, which in turn via efferent, vagal fibers sends neural signals to effector organs, known as vagal reflexes. Furthermore you can Sensory stimuli, independent from the afferent signal that migrates to the central nervous system, the local delivery of biologically active compounds (i.e., neuropeptides) of afferent nerve endings; known as axonal reflex. The vagus retains a basal level of activity which is due to the output of the efferent vagal fibers or the tone is shown. The vagus tone becomes dependent on the needs of the body, generally in response to inner or outer sensory stimuli, elevated or decreased. The former can be either central or peripheral. The effects of the vagus are caused by the neurotransmitter acetylcholine, transmitted by the efferent nerve endings, transmitted, which activates the muscarinic cholinergic receptors on the target cells.

A change Vagus tone is used in people for acute treatment of a pathophysiological Condition and used to treat certain diseases. For example are certain heart diseases with a vagally transmitted Slowing of heart rate (i.e., bradyarrhythmias). This slowing down can make the patient's well being hemodynamic affect. There is also considerable evidence that the vagal reflexes and the vagal, afferent, axonal reflexes to the pathophysiology and the symptomatology of asthma and other obstructive lung diseases contribute.

existing approaches to change of vagus tone are based on the pharmacological adaptation of the function vagal, efferent fibers. For example, the vagus tone by blocking the muscarinic cholinergic receptors as well by the inhibition of acetylcholinesterase, an enzyme that Acetylcholine degrades, be adapted. In fact, they are anticholinergic drugs very effective in the treatment of bradyarrhythmias with one acute myocardial ischemia keep in touch. These medicines are also effective bronchodilators in chronic, obstructive lung diseases. However, there is currently no therapeutic approach to the axonal reflexes The goal is to identify the specific pathophysiological conditions, such as For example, asthmatic bronchoconstriction, aggravate.

The Number of people in the United States and others developed countries Those who suffer from asthma have over the last twenty years doubled. The medical expenses associated with asthma in the United States in 1990 was $ 6.2 billion estimated. nowadays It is estimated that 10% of the world's population suffer from asthma. Furthermore, the worldwide number of asthmatics continues to increase. This trend the increasing mortality as a result of asthma is due to decreasing mortality from other diseases and given our better understanding the pathophysiology of asthma paradox. This situation is based probably at least partly due to the lack of new therapeutic Application methods that include those that also affect the neural Aim of the disease.

Of the Vagus transfers too neurogenic, human fainting (i.e., vasovagal syncope). A vasovagal reaction is due to an inappropriate decrease in the Blood pressure and / or heart rate. patients which are considered to be under a vasovagal Syncope are undergoing a clinical trial (i.e. Tilting test), in which the triggering of fainting by a head tipping over in the present or absence of drugs (eg, isoproterenol). This is a chore and expensive test. Furthermore, currently no diagnostic procedure available, to quantify the severity of this pathology.

Adenosine 5'-triphosphate (ATP) is a purine nucleotide found in every cell of the human body where it plays a major role in cellular metabolism and energetics. Outside the cells, however, ATP has various effects on many different tissues and organs. It is known that the effects of extracellular ATP are transmitted by certain cell surface receptors, the P ₂ purine receptors. These receptors are divided into two families: P _2x and P _2y (Abbracchio and Burnstock, Pharmacol Ther. (1994) 64, 445-475). The classification relies on certain aspects of signal transduction elicited by the activation of these receptors as well as the relative agonist activity of ATP and ATP analogs in various systems. For example, P _2x purine receptor transmitted responses are characterized by the order of agonist efficiencies of α, β-methylene ATP that is greater than β, γ-methylene ATP greater than ATP and 2-methylthio-ATP (these two are the same).

Therefore, it has been recognized that purine receptors are unique and that their stimulation initiates certain mechanisms. It is known that extracellular ATP affects the neural elements via the activation of a P _2x purine receptor.

Trezise et al. Br. J. Pharmacol. (1993) 110, 1055-1060 have shown that ATP can depolarize rat vagal fibers in vitro and that this effect is transmitted by P _2x purine receptors. However, these results are not applicable to the autonomic nervous system of humans for a variety of reasons. First of all, single cell assays do not address the problems of whole tissue related purine metabolism. In addition, it is uncertain whether tissues in vitro express the same receptor types as in vivo. Furthermore, work done with ATP in rats can not be extrapolated to humans because rats lack certain types of afferent-efferent ATP-induced reflex loops found only in cats, dogs, and humans.

ATP has been used as a therapeutic in human patients. For example, ATP was for many years for the acute treatment of paroxysmal, supraventricular tachycardia used. It is, however, assumed that the mechanism the action of ATP at this point the degradation of ATP to adenosine and the effect of adenosine on the specialized tissue of the heart (i.e., atrio-ventricular Node). The use of adenosine at this point is actually the subject by Belardinelli et al. U.S. Patent No. 4,673,563. It was also shown that ATP works in animal models and in people against cancer. However, the mechanism of action closes the ATP at this point the immune system and / or the direct effect on tumor cells and is independent of the autonomic nervous system. The Use of ATP as an anticancer treatment is the subject of Rapaport U.S. Patent No. 5,049,372.

The present invention provides a unique approach to altering vagal tone and vagal axonal reflexes in humans by activating and blocking P _2x purin receptors on afferent vagal nerve terminals in vivo.

Summary the invention

In one aspect, the present invention provides the use of an antagonist or an allosteric modifier of P _2x purine receptors located on vagal afferent nerve terminals for the manufacture of a medicament for reducing vagal tone in a mammal which is undesirable under one high vagus tone suffers from related condition.

Of the Antagonist may be pyridoxal phosphate-6-azophenyl-2 ', 4'-disulfonic acid. The condition may be asthma, pulmonary embolism or bradyarrhythmia.

In another aspect, the present invention provides the use of a mediator of a P _2x purine receptor disposed on a vagal afferent nerve end in the manufacture of a medicament for diagnosing abnormal vagal tone, wherein the medicament is for administration to a patient in that the vagus reflex triggered by the mediator on the patient can be measured and compared to a standard reflex, whereby a reflex which deviates from the standard reflex indicates an abnormal vagal function.

Of the Abnormal vagus tonus can be associated with vasovagal syncope stand.

These and further aspects of the invention will become more detailed below described.

Short description the figures

1 is a schematic representation of the pulmonary-pulmonary and axonal reflexes, which are the subject of the invention.

2 is a bronchogram of a control (basic conditions) (Panel A) and a bronchogram (Panel B) showing the pronounced bronchoconstriction induced by the administration of ATP (Panel B).

3 (A) shows an electrocardiogram (ECG) (B) the systemic arterial blood pressure (BP, mm Hg), (C) the pulmonary air flow (AF, 1 / min) and (D) the tracheal pressure (TP, mm H ₂ O) from a dog after administration of ATP (marked by an arrow, sec. 0).

detailed Description of the present invention

The present invention provides a novel approach to altering the autonomic nervous system vagus tonus. The treatment States associated with the parasympathetic branch of the autonomic nervous system have generally focused on altering the efferent portion of the vagal system. The present invention is based on the new approach of altering the afferent nerve flow, which in turn ultimately produces an altered response of the efferent fibers. The altered reflex may be cardio-cardial or pulmonary-pulmonary.

The cardio-cardiac reflex involves the afferent signal that is triggered in the left ventricle of the heart and travels to the brain where it is centrally processed. The result of central processing is an efferent, neural signal that reaches the heart to cause a slowing of the heart rate and a decreased force of cardiac muscle contraction. The pulmonary-pulmonary reflex similarly consists of afferent and efferent signaling as well as central processing, but the efferent signaling of this reflex reaches the lungs to cause bronchoconstriction. 1 illustrates the pulmonary-pulmonary reflex. In both reflexes, the efferent nerve terminals release acetylcholine, which acts on target cells, ie it slows the heart rate or causes constriction of the bronchi of the lung. These reflexes are protective mechanisms of the body, the cardio-cardiac reflex reduces the workload of the heart and thus reduces the oxygen demand. The pulmonary pulmonary reflex protects the lungs by limiting the amount of harmful material entering the lungs. In the same way as patients receive drugs to lower their body temperature, with the increase in temperature being a protective mechanism against bacterial infection, there is a need, in certain pathophysiological conditions, to alter cardio-cardiac and pulmonary-pulmonary reflexes.

at In one aspect of the invention, the vagal reflexes of a Patients changed and the extent of Response can be observed. According to this embodiment the efferent nerve signal is observed and recorded with the Standard of efferent nerve signal volume compared with a normal vagal function is connected. A deviation from the standard, d. H. a normal vagus response, will serve the clinician in determining the severity of the condition of one To help patients, and to indicate appropriate treatment. A standard vagus response is that of a healthy person. As of Skilled would be seen could one Standard response can be obtained by making the vagal reflex more healthy Measures patients in response to a chosen mediator.

The vagus has also been implicated in the pathophysiology of the acute phase of pulmonary embolism. The mechanism of increased vagal tone was not known at this point. However, according to the present invention, ATP released from activated platelets in the lungs is believed to activate P ₂ purine receptors located on vagal afferent nerve terminals, thereby inducing a pulmonary-pulmonary vagal reflex. This reflex causes bronchoconstriction and bronchial secretion. Both of these, bronchoconstriction and mucous congestion in the bronchi, which are commonly found in patients at the time of pulmonary embolism, contribute to the causes of death at this point.

According to others Aspects of the invention can while the vagus reflexes triggered by the acute phase of the pulmonary embolism administered to the patient, antagonistic mediator be suppressed.

According to the present invention, the vagus tone can be changed by the administration of one or mediators. Mediators suitable for the purposes of the present invention act on P _2x purine receptors on the afferent nerve terminals.

The Administration of one or more mediators is by a special to prefer targeted administration. For example, localized Catheters are used to target the mediator To administer the target.

An antagonist is administered when the vagus tone is too high and / or to suppress axonal reflexes. For example, patients suffering from asthma or other obstructive airways disease would benefit from the present invention. According to this method, an antagonist of the P _2x purine receptor, such as pyridoxal phosphate-6-azophenyl-2 ', 4'-disulfonic acid, can be administered to lower the vagus tone.

at of the present invention the mediators of the present invention in therapeutically effective Quantities according to the expert administered by recognized procedures.

The manner of administering the mediators includes any means that produce contact of the active ingredient with the agent's site of action in the body of a mammal or in a body fluid or tissue. These modes of administration include oral, topical, hypodermic, intravenous, intramuscular and intraparenteral methods of administration. However, they are not limited to these. The mediator can be reached by a ka directed at the site of the afferent nerve endings be administered. In the practice of the invention, the mediators may be administered alone or in combination with other compounds used in the invention. Other pharmaceutical compounds are preferably administered with a pharmaceutically acceptable carrier selected on the basis of the chosen route of administration and standard pharmaceutical practice.

The Administration of the compounds to mammals, preferably humans, is preferably carried out in therapeutically effective amounts. The at a given dose will be influenced by factors such as the pharmacodynamic properties of the compound, the Type and route of administration, age, health and the weight of the recipient, the Nature and extent of Symptoms, the type of concurrent treatment, the frequency of treatment and the desired Effect, depend.

It It is considered that the daily Dose of a compound used in the invention in the range of about 1 μg to approximately 100 mg per kg of body weight, preferably about 10 μg to approximately 20 mg per kg per day, will be. Pharmaceutical compositions can as a single dose, as divided doses or continuously administered become. The skilled person will be able to, based on the considerations this invention, the dose, the form and the amount only with routine experimentation to determine.

When pharmaceutical composition can be administered parenterally, in sterile, more fluid Be in a dosage form or topically in a carrier. The mediators can according to standard procedures in the field of pharmaceutical preparations be formulated in administration forms. See Gennaro Alphonso, ed., Remington's Pharmaceutical Sciences, 18th Ed., (1990) Mack Publishing Company, Easton, Pennsylvania.

For the parenteral The carriers can be administered with a suitable carrier or thinner, such as water, an oil, a saline solution, aqueous Dextrose (glucose) and related sugar solutions, and a glycol, such as Propylene glycol or polyethylene glycol, mixed. Solutions for parenteral administration preferably contain a water-soluble salt of the compound. Stabilizers, antioxidants and preservatives can also be added. Suitable are sulfite and ascorbic acid, citric acid and their salts and sodium EDTA. Suitable preservatives include Benzalkonium chloride, methyl or propylparaben and chlorobutanol.

The The following examples are illustrative and not intended to to limit the present invention.

Examples

The experiments were carried out as in Pelleg and Hurt, J. Physiol. (1996) 490.1, 265-275. The experiments were performed on anesthetized (sodium pentobarbital, 30 mg kg ^-1 plus 3 mg kg ^-1 ', h ^-1 IV) dogs (17.0 ± 0.6 kg, both sexes), which were artificially aired using a ventilator were ventilated. The physiological range for the arterial blood pH, P _O2 and P _CO2 (7.32-7.42, 85-110 mm Hg and 28-41 mm Hg, respectively) was maintained by adjusting the ventilation rate and tidal volume as well as supplemented O ₂ receive. The body temperature was maintained with a heated mattress (rectal temperature range 36.2-37.2 ° C). Systemic arterial blood pressure was determined with a Millar pressure transducer located in the descending aorta. A peripheral vein was cannulated for administration of a physiological saline solution and for maintenance of anesthetic doses. The catheters were inserted over the right femoral vein and the left atrial appendage and placed in the right atrium and left atrium, respectively, for administration of the test solutions. For intrapulmonary administration of the drugs and test compounds, a Swan-Ganz catheter was inserted via a femoral vein and placed in the distal part of the right pulmonary artery. The thorax was opened by means of a longitudinal sternotomy. The right, cervical, vagosympathetic strand was exposed by a mid-cervical longitudinal incision of the skin and a careful dissection of the neck muscles and connective tissue. The corners of the cut skin were lifted and secured to form a well that was filled with warm (37 ° C) mineral oil. A section of the vagosympathetic strand was placed on a small plate of black perspex, and fine branches were separated from the main bundle by careful dissection using microsurgical aids and a dissecting microscope (Model F212, Jenoptik Jena GmbH, Germany).

The extracellular neural action potentials were recorded using a custom bipolar electrode consisting of two platinum-iridium wires (1.25 x 0.0125 cm) and connected via a shielded cable to a high-impedance differential preamplifier (Model AC 8331, CWE Inc.). , Ardmore, PA, USA). The output of the differential preamplifier was fed to a differential post-amplifier (Model BMA-831 / C, CWE, Inc.). Isolated fibers were applied to the platinum wire pair. Vagus C fibers with chemosensitive ends have a sparse, irregular discharge that is never associated with cardiac or respiratory cycles. Confirmation of fiber type was obtained by first: observing the response to capsaicin (10 μg kg ^-1 , intra-right atrial bolus); secondly, the response to mechanical stimulation of the lung by gently exploring with a forzeps and inflating the lungs to 2-3 times the lung volume; and, third, determine the speed of conduction using a stimulating electrode located distal to the initial recording site.

One subgroup of animals was treated with PTX (30 μg kg ^-1 , consciously placed in a peripheral vein of the animals) 48 h before the experiment. (PTX was donated by Dr. E. Hewlett, University of Virginia, Charlottesville, VA, USA). The animals showed no signs of suffering during this period. These animals were subjected to glucose tolerance experiments before and 48 h after PTX administration to confirm PTX intoxication. The test consisted of the administration of a bolus of dextrose (1.1 g kg ^-1 , IV) and the subsequent collection of blood samples (5 ml, every 10 min). The glucose and insulin levels in the blood samples taken during this test were determined by the Diagnostic Laboratory at Cornell University, New York State College of Veterinary Medicine, Ithaca, NY.

The purine compounds (ATP, adenosine 5'-diphosphate (ADP), adenosine 5'-monophosphate (AMP) and adenosine; 3-6 μmol kg ^-1 and capsaicin (10 μg kg ^-1 ) were used as a rapid bolus in the right atrium (5 ml test solution + 5 ml physiological saline) or into the right pulmonary artery (1 ml test solution + 3 ml physiologic saline rinse). When added to the latter, smaller doses were used, ie 0.5-3 μmol kg- ¹ for the purine compounds and 1-5 μg kg- ¹ for capsaicin. α, β-methylene-ATP (α, β-mATP) and β, γ-methylene-ATP (β, γ-mATP) were only described as one low dose (0.75 μmol kg ^-1 ) to avoid systemic side effects The volume controls consisted of either 5 + 5 ml or 1 + 3 ml of physiological saline All injections were made in the same way by the same person To exclude the involvement of baroreceptors in recorded neural activity, the let before and after a bolus of nitroglycerin (1 mg, IV; n = 5). The effect of ganglionic transmission blockade on the action of ATP and capsaicin was determined by the administration of hexamethonium (10 mg kg ^-1 , IV; n = 7).

To determine the purine receptor subtype conferring the effect of ATP on the pulmonary vagal nerve terminals, ATP and capsaicin were given before (control) and after administration of either the selective P _2x purine receptor antagonist pyridoxal phosphate-6-azophenyl- 2 ', 4'-disulfonic acid (PPADS, 15 mg kg ^-1 , IV, 2.5-5.0 mg kg ^-1 , intrapulmonary artery, n = 6) or the selective P _2y purine receptor antagonist, reactive blue 2 ( Reactive Blue RB2, Cibacron Blue 3GA, Sigma; 7.7 mg kg ^-1 , IV; n = 4).

At the end of the experiments, the animals were sacrificed using pentobarbital (100 mg kg ^-1 , IV) plus 3 M KCl (10 ml, IV).

The Results are expressed as means ± standard deviation.

example 1

effect pattern of capsaicin and ATP and ATP analogs

In anesthetized dogs with stable sinus rhythm, a sinus cycle length of 443 ± 25 ms, and mean systemic arterial blood pressure of 89 ± 6 mm Hg, right-sided arterial capsaicin administration (10 μg kg ^-1 ) elicited an accumulation of action potentials in the right , cervical vagus fibers, which was associated with a transient slowing of the heart rate and a fall in arterial blood pressure. Similar responses were recorded on forty-six fibers in thirty-eight dogs. ATP administration caused similar effects, ie an accumulation of action potentials in the same fibers, a transient prolongation of the sinus cycle length and a decrease in systemic arterial blood pressure (ie capsaicin and ATP reduced the blood pressure to a maximum of 20 ± 4 and 58 ± 3%, respectively). ). The time to maximum, negative, chronotropic effect of ATP was significantly shorter than the time to maximal vasodilatory effect. The elapsed time from the moment of injection of capsaicin and ATP to the beginning of the neural impulses and the duration of the triggered impulses were similar. Much smaller amounts of ATP (0.5-3 μmol kg ^-1 ) and capsaicin (1-5 μg kg ^-1 ) added to the right lung artery triggered a neural activity similar to that observed, that of the right one , arterial administration of these compounds followed. The degradation products of ATP, ADP, AMP and adenosine did not stimulate the fibers (n = 30) stimulated by ATP and capsaicin.

Example 2

characterization ATP excited nerve fibers

The Fibers were otherwise calm, with no activity, with either heart rate or the respiratory cycle. The mechanical stimulation of right lung released an accumulation of action potentials in the fibers. An increase in the Tracheal pressure caused by inflation of the lungs 2-3 times of their tidal volume, stimulated the fibers. An intra-left, atrial ATP administration not to stimulate the fibers, indicating that their Ends were not in the heart and / or bronchi. The time to accumulate neural Action potentials following right atrial ATP and capsaicin (Latency) was short, about 3 s, thus eliminating the activation of bronchial fibers. The conduction velocity of the fibers was slow (0.850.13 ms, range, 0.54-1.58, n = 7), within the for Pulmonary C-fibers of dogs known speed range.

Example 3

Effect of nitroglycerin

The Decrease in systolic, arterial blood pressure caused by nitroglycerin (1 mg, I.V.), from 104 ± 12 to 77 ± 8 mm Hg (26 ± 6%, p <0.05; n = 5), did not solve one certain activity in the fibers in which the accumulation of action potentials was triggered by capsaicin and ATP.

Example 4

effects of hexamethonium

Treatment with the ganglion blocker hexamethonium (10 mg kg ^-1 , IV; n = 7) did not alter the afferent signal response elicited by either capsaicin or ATP, but markedly attenuated the negative, chronotropic actions of the two compounds. Capsaicin-induced lowering of systemic arterial blood pressure was also prevented by hexamethonium. In contrast, hexamethonium did not alter the effect of ATP on blood pressure.

The Fact that hexamethonium did not cause the temporary effects caused by ATP Decrease in blood pressure and the significantly longer time to maximum effect changed from ATP to blood pressure, versus that of capsaicin indicates that it is a non-neural Factor, d. H. Adenosine, the product of enzymatic ATP degradation, to a considerable extent the peripheral, vasodilatory effect transmits from ATP.

Example 5

ATP signaling at pulmonary C-fiber ends

Since neither ADP nor AMP nor adenosine (given in equimolar doses in the same way as ATP) elicited action potentials in any of the tested fibers, it was hypothesized that P ₂ purine receptors confer the effect of ATP. Several different pharmacological agents have been used to test this hypothesis.

First, the partially degradable ATP analogs, β, γ-mATP (0.75 μmol kg ^-1 ), elicited neural action potentials in none of the examined fibers (5 fibers in 5 dogs). In contrast, α, β-mATP (0.75 μmol kg ^-1 ) elicited accumulations of action potentials in these fibers (n = 7), which had longer periods (2-5 min) of increased activity compared to pre-α, β -MATP conditions followed.

Second, the selective P _2x purine receptor antagonist PPADS markedly attenuated the number of pulses triggered by ATP in the pulmonary vaginal C fibers (n = 6). Intra-right, pulmonary PPADS administration reduced the number of action potentials elicited by intra-right pulmonary ATP administration in a time-dependent manner. In contrast, PPADS did not affect the neural response to intra-right, pulmonary-applied capsaicin.

Third, the P _2y purine receptor antagonist RB2 did not affect the effects of ATP or capsaicin on vagal pulmonary afferent C fibers (n = 4).

During ATP and capsaicin stimulate the same afferent fibers the different potentials and answers of the two compounds on the P2 purine receptor antagonist PPADS suggest that different receptors transmit their effects.

Examples 1-5 show that an intra-right atrial ATP bolus triggers a transient accumulation of action potentials in cervical vagal fibers. Similar activity was elicited by capsaicin given in the same way. Neural activity was triggered in otherwise quiet, slow-conducting fibers. Adenosine, AMP or ADP did not trigger this activity. α, β-mATP was much more potent than ATP, while β, γ-mATP was inactive. PPADS but not RB2 eliminated this effect of ATP and neither PTX Hexamethonium prevented this effect of ATP.

Example 6

ATP stimulates pulmonary, vagal, afferent C fiber ends by activating P _2x purine receptors

The fact that adenosine, AMP and ADP, unlike ATP, did not elicit neural responses (Example 1), indicates that the effect of ATP is transmitted through a P2 purine receptor. Furthermore, the structure-function cascade: α, β-mATP >> ATP >> β, γ-mATP, as shown in Example 5, clearly indicates that the ATP-activated P2 purine receptor was the P _2x sub-type. This is supported by the data obtained with the P ₂ purine receptor antagonists (Example 5). In particular, PPADS, a P _2x purine receptor antagonist, but not RB2, a P _2y purine receptor antagonist, effectively blocks the effect of ATP on the pulmonary, vagal, afferent C fiber nerve endings.

Example 7

ATP-induced bronchoconstriction in the dog

ATP (8 μmol / kg) was given as a rapid bolus into the right atrium of the anesthetized dog's heart. Eight seconds later, a bronchogram was obtained using tantalum powder and digital fluoroscopy. 2 is a bronchogram of a control (basic conditions) (Panel A) and a bronchogram (Panel B) showing the marked bronchoconstriction induced by ATP administration (Panel B). The effect of ATP was transient and all observed parameters returned to baseline within 120 seconds.

Example 8

effects from ATP to the respiratory airflow

ATP (8 μmol / kg) was given as a rapid bolus into the right atrium of the anesthetized dog's heart. 3 shows the electrocardiogram (ECG), the systemic arterial blood pressure (BP, mm Hg), the pulmonary airflow (AF, 1 / min) and the tracheal pressure (TP, mm H ₂ O) of the dog after ATP administration (with marked by the arrow, sec. 0). How through 3 ATP exerted marked, negative, chronotropic, and dromotropic effects on sinus node automatism and AV node conduction, reduced BP and AF, and elevated TP. All of these effects were transient and markedly attenuated by bilateral cervical vagotomy (not shown).

Example 9

effects from ATP to the cardiac-cardiac reflex

Equimolar doses (0.5, 1.0 μmol / kg) of ATP and adenosine were given as rapid boluses in the left coronary artery (LM), the circumflex ramus (Cfx) and the interventricular anterior ramus (LAD) in closed anesthetized dogs Chest (n = 5) given before and after bilateral cervical vagotomy. The percent maximum extension of the sine cycle length (% ΔSCL) and the maximum time effect (t _p ) were determined. % ΔSCL and t _p were 220 ± 62% and 2.1 ± 9.3 sec, and 14.5 ± 5% and 7.4 ± 1.3 sec for ATP and adenosine, respectively (p <0.01). Bilateral cervical vagotomy either prevented or significantly attenuated the effect of ATP. In the latter case, there was no difference between the effects of ATP and adenosine and their t _p was similar. The cascade of site activity was for ATP LM >>Cfx> LAD. Thus, ATP triggers a vagal reflex by stimulating the vagal afferent nerve terminals in the left ventricle. This reflex transmits the negative, chronotropic activity of ATP and is independent of adenosine, its enzymatic degradation product.

Claims (7)

Use of an antagonist or allosteric modifier of P _2x purine receptors located on vagal afferent nerve terminals for the manufacture of a medicament for reducing vagal tone in a mammal suffering from an undesirably high vagal tone related condition. Use according to claim 1, characterized that the antagonist is pyridoxal phosphate-6-azophenyl-2 ', 4'-disulfonic acid. Use according to claim 1 or 2, characterized that the condition is asthma. Use according to claim 1 or 2, characterized that the condition is pulmonary embolism. Use according to claim 1 or 2, characterized that the condition is bradyarrhythmia. Use of a mediator of a P _2x purine receptor disposed on a vagal afferent nerve end, in the manufacture of a medicament for diagnosing abnormal vagal tone, wherein the medicament is for administration to a patient such that the vagus reflex triggered by the mediator on the patient can be measured and compared to a standard, with a reflex that deviates from the standard reflex indicating an abnormal vagal function. Use of the mediator according to claim 6, characterized characterized in that the abnormal vagus tone is associated with a vasovagal Syncope is related.